Electrochemical Amination. Selective Functionalization of para- and ortho-Anisidines in Aqueous Sulfuric Acid Solutions

Abstract

The processes of the electrochemical amination of para- and ortho-anisidines using hydroxylamine and the Ti(IV)/Ti(III) mediator system are studied in aqueous solutions of 4–14 M sulfuric acid. The functionalization of para-anisidine results in the formation of 4-methoxy-1,3- and 4-methoxy-1,2-phenylenediamines with a current efficiency of up to 64.3 and 0.56%, respectively. When ortho-anisidine is aminated, 4-methoxy-1,3-phenylenediamine is the only substitution product; its current efficiency reaches 61%. Under the conditions that favor synthesis of 4-methoxy-1,3-phenylenediamine from anisidines, full conversion of hydroxylamine is observed and the current efficiency of the diamino compound corresponds to the yield per amino radical source.